Acne is a common inflammatory pilosebaceous disease characterized by comedones, papules, pustules, inflamed nodules, superficial pus-filled cysts, and in extreme cases, sinus formation and deep inflammation, sometimes associated with purulent sacs.
The pathogenesis of acne is complex. An interaction between hormones, keratinization, sebum, and bacteria somehow determines the course and severity of the disease. Acne begins at puberty when the increase of androgens causes an increase in the size and activity of the pilosebaceous glands. The earliest microscopic change is intrafollicular hyperkeratosis, which leads to restriction of the pilosebaceous follicle with consequent formation of the comedone composed of sebum, keratin, and microorganisms, particularly Propionibacterium (Corynebacterium) acnes. Lipases from P. acnes break down triglycerides in the sebum to form free fatty acids (FFA), which irritate the follicular wall. Retention of sebaceous secretions and dilation of the follicle may lead to cyst formation. Rupture of the follicle with release of the contents into the tissues induces an inflammatory reaction which heals with scarring in severe cases.
Acne tends to appear during puberty and to fade away again, usually spontaneously when growth has stopped. Only rarely does it recede before the age of 20 and occasionally it is still to be found at the age of 30 and beyond. The face, back, and shoulders are the predominant areas affected. Particularly with the face, severe cases can cause alterations resulting in considerable disfigurement with significant psychological burdens for the afflicted person.
Acne can be treated by topical application of various lotions, salves, and the like or by, for example, localized treatment with sulphur, resorcinol, salicylic acid, benzoyl peroxide, vitamin A acids, antibiotics such as erythromycin, and the like.
Salicylic acid is a well recognized anti-acne active ingredient which causes a reduction in intercellular cohesion of the corneocytes (see, C. Huber et al., Arch. Derm. Res. 257, pp. 293-297, 1977). It has also been postulated that salicylic works by dissolving the existing keratin plugs as well as preventing the formation of new ones. In order to best exert its skin benefits, the ideal anti-acne composition should deliver and retain optimal concentrations of salicylic acid in the stratum corneum with less penetration through the skin and into the general circulation. Also, compliance by the user to a regimen of treatment involving repeated applications is important. However, salicylic acid tends to be somewhat drying and irritating and can often cause peeling, thereby causing individuals to refrain from using salicylic acid products as frequently and copiously as is necessary to obtain an optimum benefit. Thus, user compliance with current salicylic acid compositions is less than ideal.
Panthenol is the alcohol form of pantothenic acid, a well known nutritional factor. The use of panthenol in skin care products, e.g. shampoos and skin creams is also known. It has been reported that panthenol, for example in combination with zinc oxide, provides an acceleration of superficial wound healing (see, H. Weise et al., "Acceleration of Superficial Wound Healing by Panthenol Zinc Oxide", Cosmetics and Toiletries, vol. 103, pp. 79-84, October 1988).
It has been found in the instant invention that the combination of salicylic acid and pantothenic acid or a pantothenic acid derivative, preferably dexpanthenol, provides compositions which are effective for the treatment of acne that are less irritating and drying to the skin than conventional salicylic acid compositions. These compositions have improved user acceptance and thus promote better user compliance with a concomitant overall improved anti-acne benefit. It has also been found that these compositions are useful for effacing and preventing wrinkles and atrophy in mammalian skin.
It is therefore an object of the present invention to provide methods for the treatment of acne in mammalian skin. Another object of the present invention is to provide methods for the treatment of acne which are gentler, and thus less irritating and drying to the skin. A further object of the present invention is to provide methods for the treatment of acne utilizing a combination of the active ingredient salicylic acid with pantothenic acid or a pantothenic acid derivative. An even further object of the present invention is to provide methods for the treatment of acne utilizing a combination of the active ingredient salicylic acid with dexpanthenol. A still further object of the present invention is to provide less irritating compositions for the treatment of acne. A yet further object of the present invention is to provide a method of regulating wrinkles and/or atrophy in mammalian skin.
These and other objects of this invention will become apparent in light of the following disclosure.